Electron discharge tube



Jul 4, 19

A. e. CLAVIER 2,164,905

ELECTRON DISCHARGE TUBE Filed March 24, 1936 FIG.

INVENTOR 14.6. CLAV/ER BY ATTORNEY Patented July 4, 1939 PATENT OFFICE ELECTRON DISCHARGE TUBE Andr Gabriel Clavier, Paris, France, assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application March 24, 1936, Serial No. 70,557

In France April 29, 1935 4 Claims. (cram-27.5

This invention relates to improvements in electron discharge tubes or devices and their connections.

One object of this invention is to provide new 5 construction and m'ountingsof electrodes in such tubes operable at short or ultra-short waves (micro-ray) The invention may also find application in other arts.

Another object of the invention is to improve W the stability of the frequency characteristics of such tubes.

A further object of the invention is to supply more efiicient constructions and in particular per- I p it a greaterldissipationj of energy than in the 1:) reviously known tubes.

In the following description it'will be seen that means are providedto define the high frequency potential at one or more points of one or more electrodes of an electron discharge tube.

The invention will be understood more clearly from the following detailed description with reference to the accompanying drawing in which:

Figure 1 represents in section an improved construction of a tube employing features of this invention; and e Fig. 2shows a side view in section of the structure of the tube of Fig. l.

The embodiment shown in the drawing relates to a three-electrode tube of the type generally known as'Barkhausen oscillators in which a socalled oscillating electrode is maintained at a continuous positive potential, While another socalled reflecting electrode is maintained'at a"neg-' ative potential. In' such a tube it is possible, by

suitable adjustment of the potentials, to obtain electrical "oscillations of very high frequencies along the oscillating electrode.

In Fig. l, the enclosing vessel of the tube is designated as I, and 2 is the extension of the press to supporting insulating members 3 and"4 in which are sealed ate and 8, and l and 8, rods 9 and it and H and'lZrespectively. The rods 9 and lil are connected at suitably chosen'points of the oscillatingelectrode [3. To the rods 9 and are fixed'connections 'i l-jand [5 serving to conduct to the outside of the tube the ultrahigh frequency oscillations produced along the oscillating electrade it, or, conversely to lead'to'the'oscillating electrode l 3 ultra-high frequency'oscillations pro- C' duced on a receiving device connected to the conductors Mann-F51- The oscillating electrode .3 is provided at its two extremities l6 and I! with metallic plates l8 and I9 whose electrical role will be hereinafter defined. These plates are supported by the rods I I and l 2 mentioned above.

The reflecting electrode 2%! is maintained in position byarod 2|, shown in Fig. 2, serving to apply a suita'bl'e potential to this electrode 20. The extremities of the reflecting electrode also may be provided, as shown in Fig. 1, with metallic plates or flanges 22 and 23 placed substantially parallel to the flanges l8 and is with which the oscillating electrode is provided. The axis of this structure is constituted by a source of electrons represented here in the form of a cathode 24 in filament form, maintaine'd'in position between the rod 25 and the spring 26. The heating current for the cathode is supplied through the rods 21 and 28 shown in Fig. 2.

Ifnecessary, there may be provided inside the vacuum tube a cup 29 containing a substance such as magnesium to absorb the residual gases in well-known manner.

Instead of directly including the oscillating electrode in the utilization circuit, the structure which has just been described permits the coupling of the oscillating electrode as loosely as desired with theutilization circuit. This arrangement has great advantages; in particular it permits the attainment in'a given oscillator tube, of a considerably improved frequency stability owing to the fact that the utilization circuit reacts only slightly on the circuit which determines this frequency, and, in the case of a receiver tube, a material'increase is the selectivity of the receiving circuit.

-=In the arrangement described, the circuit determiningthe frequency is entirely inside the tube and is constituted by the oscillating electrode alone, means being provided to create tension nodes at the extremities of this oscillating electrode. Among the means which may be employed to this end may be mentioned the addition of flanges" at the ends of the oscillating electrode. These flanges cause reflections at the ends of the oscillating electrode, which result in the formation at points It and H of ultra-high fre: quency tension nodes. In certain cases it may be Well" to provide also flanges 22 and 23 on the refleeting electrode, which improves the symmetry of the device and assists in the dissipation of the heat generated in the system.

v In this type of tube, the length of the wire of the oscillating electrode preferably should be substantially equal tothe optimum wave-length .7

or in a more general manner to a multiple of this wave-length. This condition is preferable to the case in which there would be an odd number of half-waves along the oscillating electrode because it permits the coupling of the utilization circuit symmetrically by the connections 9 and I to the oscillating electrode.

Let us take as an example the case in which the length of wire of the oscillating electrode is equal to a wave-length. The outer circuit may then be connected to the oscillating electrode by means of two parallel conductors l4 and I5, Fig. l. The points of the oscillating electrode to which these conductors are connected are placed substantially a quarter of a wave-length away from the two extremities of the oscillating electrode. These conductors 9 and I0 pass through holes provided in the reflecting electrode 20. It is, moreover, an advantage to provide perforations in the reflecting electrode or to construct it of metal gauze so as to accelerate the removalof the heat developed in the system.

It will be noted that the addition of flanges to the extremities of the oscillating and reflecting electrodes also facilitates the dispersion of heat.

It may be noted also that the new construction of' oscillating electrode described here fulfils the part of a tank circuit to which the utilization circuit is coupled.

In the particular example described above, it will generally be well to choose for the length of the connections I5 and [4 an odd number of quarter wave-lengths, from the electrodes of the tube to a utilization element in which a maximum current is desired.

As these connections l4 and I5 pass through the vessel 1, it is desirable to seal these connections to th vessel at points a very short distance from the axis of the structure or at a distance equal to half a wave-length so as to maintain the losses due to this sealing at as low a value as possible.

It may be noted that the negative linear conductance along the oscillating electrode is in- 1 creased by the presence of the flanges l8 and 22 for the same dispersion of heat on the electrodes, the same diameter of oscillating electrode and the same operating wave-length. One of the reasons for this increase in the negative conductance is that for a particular wave-length the wire of the oscillating electrode is chosen preferably equal to this wave-length instead of a valve near 1.25 which is optimum in the case of the structure of the same type not comprising flanges at the extremities of the oscillating electrode.

A suitable potential can easily be applied to the oscillating electrode by means of a connection from a suitable source to one of the flanges of said electrode. This conductor can be brought to the outside of the tube through the base of the latter. This arrangement greatly simplifies the mounting of the tube, because all the leads (cathode, oscillating electrode and reflecting electrode) have their connections brought to the base of the tube and no loss is introduced, therefore, along the high frequency connections to the oscillating electrode.

From the point of view of the arrangement of the circuits, the tube structure shown permits considerable simplification of the connections because the tube itself carries out the separation of the high frequency circuits from the supply circuits for the filament, oscillating and reflecting electrodes and it does not require the use of a special type of base.

It is obvious that the arrangements described have only been so described by way of example and that modifications may be made in these devices without departing from the scope of the present invention. For example, the coupling between the oscillating electrode and the transmission line terminating in a utilization apparatus may be carried out by means of either trans formers or condensers. In the case of coupling by a transformer, the connections 9 and 10 will terminate in one or more turns arranged in the vicinity of or concentric to the oscillating electrode l3; in the case of coupling by capacity, for example, small condensers in series could be used in the connections 9 and I0. Other coupling devices which will appear clearly to those skilled in the art may also be employed.

Although a cylindrical symmetry tube has been described by way of example, it is clear that the invention may be applied to tubes having other kinds of symmetries, for example, to tubes provided with plane electrodes. Likewise, the elements composing the electrodes may be utilized for various purposes, for example, in ionic or electronic discharge devices. Furthermore, the invention may, of course, be applied to a tube having any number of electrodes.

What is claimed is:

1. An electron discharge device comprising an enclosing vessel a cathode within said vessel,

a grid encompassing said cathode, disc members surrounding said grid, and leading-in conductors.

for said grid separate from and spaced from said supporting means.

2. A Barkhausen oscillator comprising an enclosing vessel, a cathode, a grid, and a reflecting electrode, disc members at the ends of said grid and connected thereto, supporting means extending from one end of said vessel and secured to said disc members, and leading-in conductors extending from the opposite end of said vessel and connected to said grid intermediate the ends thereof.

3. An electron discharge device comprising an enclosing vessel having a stem, a cathode above said stem, a grid encompassing said cathode, disc members at the ends of said grid and connected thereto, support members extending from said stem and secured to said disc members, a cylindrical electrode surrounding said grid, support means for said electrode extending from said stem, and leading-in conductors for said grid connected thereto intermediate the ends thereof and extending from said vessel at points remote from said stem.

4. A Barkhausen oscillator comprising a linear cathode, a spiral grid surrounding said cathode and coaxial therewith, metallic disc members at the ends of said grid and at substantially right angles to said cathode, a cylindrical reflecting electrode surrounding said grid and coaxial therewith, annular flanges at the ends of said reflecting electrode disposed parallel and in juxtaposition to said disc members, and leading-in conductors for said grid secured to intermediate turns thereof, said conductors extending at substantially right angles to the longitudinal axis of said grid.

ANDRE G. CLAVIER. 

